Gravity foundation structure liquefied natural gas import and export terminal and method of installation

Abstract

The application relates to a gravity type foundation structure liquefied natural gas import and export terminal and a mounting method, and belongs to the technical field of offshore liquefied natural gas import and export terminal foundation structures. The bottom of the import and export terminal is provided with a steel skirt along the periphery and in the horizontal direction, a bottom plate, a tank plate and a top plate are arranged in the horizontal direction, and a partition wall is arranged between the bottom plate and the tank plate, so that a plurality of cabins are divided. A middle space between the tank plate and the top plate is used for mounting an LNG storage tank, and the LNG storage tank is surrounded by the partition wall and is divided into a plurality of equipment cabins, so that a box structure is finally formed. The application is designed with a double-layer concrete structure and filled with ballast, so that the risk of damage of the LNG storage tank when the LNG storage tank collides with the structure is reduced. By arranging the LNG storage tank in the structure, the stability of the structure is increased by using the weight of the LNG storage tank. The application is installed in a nearshore area, so that the influence of LNG operation on the land environment is reduced, and the water depth condition is good, so that large-scale LNG ship operation is facilitated.

Description

Technical Field

[0001] This invention relates to the field of basic structure technology, and in particular to a gravity-based liquefied natural gas inlet / outlet terminal and its installation method. Background Technology

[0002] Liquefied natural gas (LNG) is mainly composed of methane and is widely recognized as the cleanest fossil fuel on Earth.

[0003] Due to the inherent safety risks associated with LNG storage and transportation, LNG terminals typically utilize land reclamation or long-distance trestle bridges to keep berths away from densely populated areas to mitigate these risks. Both of these methods involve high investment costs, difficult construction, and negative environmental impacts. With increasing domestic LNG demand and saturated terminal shoreline resources, offshore LNG import / export terminals will play a greater role in energy import and export.

[0004] Gravity-based concrete (GBS) foundations offer high load-bearing capacity, excellent durability, and good fire resistance, making them particularly suitable for the foundations of large offshore engineering platforms. These structures can be prefabricated in factories and placed offshore, avoiding the problems of high investment costs, difficult construction, and proximity to densely populated areas inherent in traditional LNG terminals. The structures include LNG storage space and can support various large and complex equipment on top, providing a favorable operating environment for LNG import and export. This allows for LNG loading, unloading, and storage operations to be carried out away from densely populated areas, expanding the functionality of LNG import and export terminals. Based on existing engineering technology reserves, the research and development of gravity-based concrete foundation structures is feasible. Summary of the Invention

[0005] This invention overcomes the shortcomings of the prior art and provides a gravity-based liquefied natural gas inlet and outlet terminal and its installation method.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The first aspect of this invention provides a gravity-based liquefied natural gas inlet / outlet terminal, comprising:

[0008] The bottom of the import / export terminal is provided with a steel skirt along the perimeter and horizontal direction, and a bottom plate, tank plate and top plate are provided in the horizontal direction;

[0009] The import / export terminal is divided into two layers, with a partition wall between the bottom plate and the tank plate, which divides it into several compartments. The central space between the tank plate and the top plate is used to install LNG storage tanks. The LNG storage tanks are divided into several ballast tanks and equipment compartments by partition walls, ultimately forming a box structure.

[0010] Furthermore, in the aforementioned gravity-based liquefied natural gas import / export terminal, the top plate of the import / export terminal supports at least the LNG receiving station's berthing equipment, loading and unloading equipment, and personnel activity buildings.

[0011] Furthermore, in the gravity-based liquefied natural gas inlet / outlet terminal, an opening is provided on the top plate of the inlet / outlet terminal to allow the upper equipment to connect with the LNG storage tank and equipment compartment.

[0012] Furthermore, in the aforementioned gravity-based liquefied natural gas inlet and outlet terminal, several layers of materials with functions such as water vapor isolation and heat insulation are provided between the LNG storage tank and the concrete.

[0013] Furthermore, in the aforementioned gravity-based liquefied natural gas inlet / outlet terminal, heating cables and a temperature control system are pre-embedded in the concrete, and the temperature of the concrete is controlled within a preset range by the temperature control system.

[0014] Furthermore, in the aforementioned gravity-based liquefied natural gas import / export terminal, before the base plate is constructed, an airbag and its inflation pipe are pre-embedded at the bottom of the base plate. The airbag has an interface reserved above it to connect with the inflation pipe inside the base plate. The airbag is used to inflate during shipment, filling the space between the base plate and the steel skirt, and then lifting the GBS.

[0015] Furthermore, a second aspect of the present invention provides an installation method for a gravity-based liquefied natural gas inlet / outlet terminal, applicable to any of the gravity-based liquefied natural gas inlet / outlet terminals described in the present invention, comprising the following steps:

[0016] Step 1: Construct a prefabrication yard on dry land near the sea, calculate the buoyancy required for floating GBS to determine the bottom elevation of the prefabrication yard, and construct a dock gate in the prefabrication yard that connects to the sea and allows tugboats to tow the GBS structure; the GBS is a gravity-based liquefied natural gas import and export terminal.

[0017] Step 2: Level the site and lay the steel bottom formwork. The steel bottom formwork is reserved with space for the GBS steel skirt to be embedded, so that the GBS concrete is in direct contact with the steel formwork.

[0018] Step 3: Install steel skirts, construct GBS base plate, ballast tank and tank plate, and arrange airbag inflation system and ballast water system in the base plate;

[0019] Step 4: Construct the ballast tanks, equipment compartments, water storage tanks, tank compartments, and roof of the GBS on three sides, reserving one side as an installation passage for the LNG storage tank;

[0020] Step 5: Install the LNG storage tank horizontally into the GBS through the pre-reserved installation channel on the side;

[0021] Step 6: Construct the reserved passageway for the water storage tank, fire-fighting tank, equipment tank, and roof slab, complete the structural construction, and install the superstructure.

[0022] Furthermore, the installation method for the gravity-based liquefied natural gas inlet and outlet terminal also includes the following steps:

[0023] Step 7: Inject ballast water into the structural ballast tanks to maintain a certain self-weight of the structure and prevent the structure from floating in the prefabrication yard during the water injection in the dock.

[0024] Step 8: Open the dock gate and inject seawater into the prefabricated dock until the water level inside the dock is the same as the sea level;

[0025] Step 9: Empty the ballast water and activate the airbag system at the bottom of the structure to slowly lift the structure.

[0026] Step 10: Start the winch to tow the structure from the dock to the sea surface and connect it to the tugboat;

[0027] Step 11: Re-inject ballast water into the structure for counterweighting to maintain balance during offshore towing transport;

[0028] Step 11: After the GBS is towed to the installation site, it is positioned using GPS and other methods to maintain the designed installation accuracy and tilt limit. After ballast water is injected and the GBS sinks to the seabed, other ballast materials are quickly injected to enable the structure to resist wind and waves. At the same time, the air in the airbag is evacuated to create negative pressure under the bottom plate, which accelerates the foundation consolidation speed and completes the installation.

[0029] Furthermore, the installation method for the gravity-based liquefied natural gas inlet and outlet terminal also includes the following steps:

[0030] The system obtains seawater density data under different environmental characteristics through big data, and introduces a graph neural network. The seawater density data under different environmental characteristics is input into the graph neural network, and the environmental characteristics are used as the first graph node.

[0031] Using the seawater density data as the second graph node, an undirected edge description relationship is constructed. The first graph node and the second graph node are connected according to the undirected edge description relationship to generate a related topology graph.

[0032] Based on the relevant topology graph, obtain the relevant adjacency matrix, construct a seawater density knowledge graph, and input the relevant adjacency matrix into the seawater density knowledge graph for storage.

[0033] The environmental characteristics of the tugboat in the target sea area are obtained, and the environmental characteristics in the target sea area are input into the seawater density knowledge graph for data matching to obtain seawater density data in the target sea area. The input amount of ballast water is then adjusted based on the seawater density data in the target sea area.

[0034] Specifically, the adjustment of the ballast water input based on seawater density data in the target sea area includes:

[0035] The buoyancy information of the gravity-based liquefied natural gas inlet and outlet terminal in the target sea area is calculated based on the seawater density data, and the ballast water volume injected into the gravity-based liquefied natural gas inlet and outlet terminal is obtained.

[0036] The mass information of the ballast water is calculated based on the amount of ballast water injected into the current gravity-based liquefied natural gas inlet and outlet terminal, and the mass information of the current gravity-based liquefied natural gas inlet and outlet terminal when no ballast water is injected is obtained.

[0037] The total mass information is calculated based on the mass information of the ballast water and the mass information of the current gravity-based liquefied natural gas inlet and outlet terminals when no ballast water is injected. The deviation rate between the total mass information and the buoyancy information is then calculated.

[0038] When the deviation rate is greater than the preset deviation rate threshold, the ballast water volume injected into the liquefied natural gas inlet and outlet terminals of the gravity-type foundation structure is adjusted until the deviation rate is not greater than the preset deviation rate threshold.

[0039] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0040] The installation location of this invention is far from densely populated areas, reducing the risks during LNG storage and transportation. The invention features a double-layered concrete structure filled with ballast material, reducing the risk of damage to the LNG storage tanks when struck by ships. By placing the LNG storage tanks inside the structure, the weight of the tanks increases the structural stability. Furthermore, the installation location is in a near-shore area with good water depth, facilitating operations for large LNG vessels. The structure utilizes a precast reinforced concrete box form and on-site settlement installation, resulting in lower construction costs, faster construction speed, better durability, and better fire resistance. Finally, the large projected area of ​​the structure, coupled with anti-slip steel skirts, reduces the foundation requirements and provides ample space for ship berthing, LNG loading and unloading operations, and personnel living and working. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained from these drawings without creative effort.

[0042] Figure 1 A schematic diagram of the structural layering is shown;

[0043] Figure 2 The bottom steel skirt arrangement diagram is shown;

[0044] Figure 3 A first schematic diagram of the installation process is shown;

[0045] Figure 4 A second schematic diagram of the installation process is shown;

[0046] Figure 5 A third schematic diagram of the installation process is shown;

[0047] Figure 6 The fourth diagram illustrating the installation process is shown;

[0048] Figure 7 The fifth diagram illustrating the installation process is shown;

[0049] Figure 8 The sixth diagram illustrating the installation process is shown;

[0050] Figure 9 The seventh diagram illustrates the installation process;

[0051] Figure 10 The eighth diagram illustrating the installation process is shown;

[0052] Figure 11 The ninth diagram illustrating the installation process is shown;

[0053] Figure 12 The tenth diagram illustrating the installation process is shown;

[0054] Figure 13 The eleventh diagram in the installation process is shown;

[0055] Figure 14 The twelfth diagram shows the installation process.

[0056] In the picture:

[0057] 1. Bottom plate, 2. Tank plate, 3. Top plate, 4. Ballast tank, 5. Steel skirt, 6. Fire compartment, 7. Equipment compartment, 8. LNG storage tank compartment. Detailed Implementation

[0058] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner. Therefore, they only show the components related to the present invention. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0059] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the scope of protection of this application. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0060] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of the above terms in this application based on the specific circumstances.

[0061] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0062] This invention relates to a reinforced concrete gravity foundation structure for offshore LNG import / export terminals. The overall structure is a box-shaped structure with rounded rectangular corners in its top view. A 1m high, 6cm thick steel skirt 5 is installed along the perimeter and horizontally at the bottom, which is embedded in the soil after installation to increase the structure's anti-slip ability. The box body consists of a bottom plate 1, a tank plate 2, and a top plate 3 in the horizontal direction, dividing the space into two layers. Between the bottom plate and the tank plate is a ballast layer with longitudinal and transverse partitions, dividing it into multiple compartments with different functions, such as ballast tanks 4, freshwater tanks, and fire-fighting compartments 6, enhancing the structure's rigidity. The central space of the LNG storage tank compartment 8 between the tank plate and the top plate is used to install LNG storage tanks, which are surrounded by multiple longitudinal and transverse partitions to form multiple equipment compartments 7. The top plate of the box body supports the LNG receiving station's berthing equipment, loading and unloading equipment, personnel activity buildings, and other facilities. Openings in the top plate allow for connection between the upper equipment and the LNG storage tanks and equipment compartments. A structural layer diagram and a steel skirt arrangement diagram are shown below. Figure 1 as well as Figure 2 As shown.

[0063] Furthermore, a second aspect of the present invention provides an installation method for a gravity-based liquefied natural gas inlet / outlet terminal, applicable to any of the gravity-based liquefied natural gas inlet / outlet terminals described in the present invention, comprising the following steps:

[0064] Step 1: Construct a prefabrication yard on dry land near the sea, calculate the buoyancy required for floating GBS to determine the bottom elevation of the prefabrication yard, and construct a dock gate in the prefabrication yard that connects to the sea and allows tugboats to tow the GBS structure; the GBS is a gravity-based liquefied natural gas import and export terminal.

[0065] Step 2: Level the site and lay the steel bottom formwork. The steel bottom formwork is reserved with space for the GBS steel skirt to be embedded, so that the GBS concrete is in direct contact with the steel formwork.

[0066] It should be noted that the present invention designs a double-layer concrete structure and fills it with ballast material to reduce the risk of damage to the LNG storage tank when the ship collides with the structure. By placing the LNG storage tank inside the structure, the weight of the LNG storage tank is used to increase the stability of the structure.

[0067] Step 3: Install steel skirts, construct GBS base plate, ballast tank and tank plate, and arrange airbag inflation system and ballast water system in the base plate;

[0068] Step 4: Construct the ballast tanks, equipment compartments, water storage tanks, tank compartments, and roof of the GBS on three sides, reserving one side as an installation passage for the LNG storage tank;

[0069] In steps 1 to 4, the construction process is as follows: Figures 3 to 4As shown, before constructing the base plate, airbags and their inflation pipes are pre-embedded at the bottom of the base plate. The airbags have pre-drilled interfaces at the top to connect to the inflation pipes inside the base plate. The airbags are used to inflate during transport, filling the space between the base plate and the steel skirt to lift the GBS.

[0070] Step 5: Install the LNG storage tank horizontally into the GBS through the pre-reserved installation channel on the side;

[0071] During the construction process, such as Figures 5 to 6 As shown. It should be noted that, on the one hand, the installation location of this invention is in a near-shore area with good water depth conditions, which is conducive to the operation of large LNG ships. On the other hand, the structure adopts the form of a precast reinforced concrete box and the construction method of on-site settlement installation, which has low construction cost, fast construction speed, good durability and fire resistance. Finally, the structure has a large projected area and is equipped with anti-slip steel skirts, which reduces the structural requirements on the foundation and provides ample space for ship berthing, LNG loading and unloading operations, and personnel production and living.

[0072] Step 6: Construct the water storage tank, fire-fighting tank, equipment tank, and roof slab with reserved passageways, complete the structural construction, and install the superstructure. The construction process in Step 6 is as follows: Figure 7 by Figure 8 As shown.

[0073] The LNG temperature is approximately -162℃. Multiple layers of insulation material are required between the storage tank and the concrete to prevent the low temperature from being conducted to the concrete, creating thermal stress and causing cracking. During the design process of the GBS structure, a detailed heat conduction analysis is necessary, considering both steady-state and transient temperature distributions, and assessing the impact of the LNG storage tank's low temperature on the concrete structure. If necessary, heating cables and temperature control systems can be pre-embedded in the concrete to maintain the concrete temperature between +2℃ and +8℃, ensuring an appropriate temperature gradient while avoiding the adverse effects of freeze-thaw cycles and thermal stress on the concrete structure.

[0074] Furthermore, the installation method for the gravity-based liquefied natural gas inlet and outlet terminal also includes the following steps:

[0075] Step 7: As Figure 9 As shown, ballast water is injected into the structural ballast tank to maintain a certain self-weight of the structure and prevent the structure from floating in the prefabrication yard during the water injection in the dock.

[0076] Step 8: As Figure 10 As shown, open the dock gate and inject seawater into the prefabricated dock until the water level inside the dock is the same as the sea level.

[0077] Step 9: As Figure 11 As shown, the ballast water is emptied, and the airbag system at the bottom of the structure is activated to slowly lift the structure.

[0078] Step 10: Figure 12 As shown, the winch is started to tow the structure from the dock to the sea surface and connect it to the tugboat; as

[0079] Step 11: As Figure 13 As shown, ballast water is reinjected into the structure for counterweight to maintain balance during towed transport at sea. Buoyancy information can be calculated based on the density characteristics of seawater in different sea areas, thereby determining the required weight of water to be injected. This can be automatically adjusted based on the density characteristics of seawater in different sea areas to achieve balance during towed transport. Furthermore, the density variation characteristics of seawater in the sea area can be predicted by considering different temperature and salinity environments, thus further determining the density of seawater in the sea area.

[0080] Step 11: As Figure 14 As shown, after the GBS is towed to the installation site, it is positioned using GPS and other methods to maintain the designed installation accuracy and tilt limit. After ballast water is injected and it sinks to the seabed, other ballast materials are quickly injected to enable the structure to resist wind and waves. At the same time, the air in the airbag is evacuated to form a negative pressure under the bottom plate, which accelerates the foundation consolidation speed and completes the installation.

[0081] Furthermore, the installation method for the gravity-based liquefied natural gas inlet and outlet terminal also includes the following steps:

[0082] The system obtains seawater density data under different environmental characteristics through big data, and introduces a graph neural network. The seawater density data under different environmental characteristics is input into the graph neural network, and the environmental characteristics are used as the first graph node.

[0083] Using the seawater density data as the second graph node, an undirected edge description relationship is constructed. The first graph node and the second graph node are connected according to the undirected edge description relationship to generate a related topology graph.

[0084] Based on the relevant topology graph, obtain the relevant adjacency matrix, construct a seawater density knowledge graph, and input the relevant adjacency matrix into the seawater density knowledge graph for storage.

[0085] The environmental characteristics of the tugboat in the target sea area are obtained, and the environmental characteristics in the target sea area are input into the seawater density knowledge graph for data matching to obtain seawater density data in the target sea area. The input amount of ballast water is then adjusted based on the seawater density data in the target sea area.

[0086] It should be noted that environmental characteristics include data such as seawater temperature and salinity. This method can predict the density of seawater under different environmental characteristics, thereby improving the stability of tugboats when towing import and export terminals and maintaining the balance of transportation.

[0087] Specifically, the adjustment of the ballast water input based on seawater density data in the target sea area includes:

[0088] The buoyancy information of the gravity-based liquefied natural gas inlet and outlet terminal in the target sea area is calculated based on the seawater density data, and the ballast water volume injected into the gravity-based liquefied natural gas inlet and outlet terminal is obtained.

[0089] The mass information of the ballast water is calculated based on the amount of ballast water injected into the current gravity-based liquefied natural gas inlet and outlet terminal, and the mass information of the current gravity-based liquefied natural gas inlet and outlet terminal when no ballast water is injected is obtained.

[0090] The total mass information is calculated based on the mass information of the ballast water and the mass information of the current gravity-based liquefied natural gas inlet and outlet terminals when no ballast water is injected. The deviation rate between the total mass information and the buoyancy information is then calculated.

[0091] When the deviation rate is greater than the preset deviation rate threshold, the ballast water volume injected into the liquefied natural gas inlet and outlet terminals of the gravity-type foundation structure is adjusted until the deviation rate is not greater than the preset deviation rate threshold.

[0092] It should be noted that this method can improve the stability of tugboats when towing import / export terminals, maintain the balance of transportation, and control the input or output of ballast water.

[0093] In summary, the installation location of this invention is far from densely populated areas, reducing the risks during LNG storage and transportation. The invention features a double-layered concrete structure filled with ballast, reducing the risk of damage to the LNG tanks when impacted by ships. By placing the LNG tanks inside the structure, the weight of the tanks increases structural stability. Furthermore, the installation location is in a near-shore area with good water depth, facilitating operations for large LNG vessels. The structure utilizes a precast reinforced concrete box form and on-site settlement installation, resulting in lower construction costs, faster construction speed, better durability, and better fire resistance. Finally, the large projected area and anti-slip steel skirts reduce the foundation requirements and provide ample space for ship berthing, LNG loading and unloading operations, and personnel living and working.

[0094] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0095] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. An installation method for a gravity-based foundation structure liquefied natural gas inlet / outlet terminal. Its features are, in, The bottom of the import / export terminal is provided with a steel skirt along the perimeter and horizontal direction, and a bottom plate, tank plate and top plate are provided in the horizontal direction; The import and export terminal is divided into two layers, and a partition wall is set between the bottom plate and the tank plate to divide it into several compartments. The central space between the tank plate and the top plate is used to install LNG storage tanks. The LNG storage tanks are divided into several ballast tanks and equipment compartments by partition walls, ultimately forming a box structure. Includes the following steps: Step 1: Construct a prefabrication yard on dry land near the sea, calculate the buoyancy required for floating GBS to determine the bottom elevation of the prefabrication yard, and construct a dock gate in the prefabrication yard that connects to the sea and allows tugboats to tow the GBS structure; the GBS is a gravity-based liquefied natural gas import and export terminal. Step 2: Level the site and lay the steel bottom formwork. The steel bottom formwork is reserved with space for the GBS steel skirt to be embedded, so that the GBS concrete is in direct contact with the steel formwork. Step 3: Install steel skirts, construct GBS base plate, ballast tank and tank plate, and arrange airbag inflation system and ballast water system in the base plate; Step 4: Construct the ballast tanks, equipment compartments, water storage tanks, tank compartments, and roof of the GBS on three sides, reserving one side as an installation passage for the LNG storage tank; Step 5: Install the LNG storage tank horizontally into the GBS through the pre-reserved installation channel on the side; Step 6: Construct the water storage tank, fire-fighting tank, equipment tank, and roof slab with reserved passageways, complete the structural construction, and install the superstructure; Step 7: Inject ballast water into the structural ballast tanks to maintain a certain self-weight of the structure and prevent the structure from floating in the prefabrication yard during the water injection in the dock. It also includes the following steps: The system obtains seawater density data under different environmental characteristics through big data, and introduces a graph neural network. The seawater density data under different environmental characteristics is input into the graph neural network, and the environmental characteristics are used as the first graph node. Using the seawater density data as the second graph node, an undirected edge description relationship is constructed. The first graph node and the second graph node are connected according to the undirected edge description relationship to generate a related topology graph. Based on the relevant topology graph, obtain the relevant adjacency matrix, construct a seawater density knowledge graph, and input the relevant adjacency matrix into the seawater density knowledge graph for storage. The environmental characteristics of the tugboat in the target sea area are obtained, and the environmental characteristics in the target sea area are input into the seawater density knowledge graph for data matching to obtain seawater density data in the target sea area. The input amount of ballast water is then adjusted based on the seawater density data in the target sea area.

2. The installation method of a gravity-based foundation structure liquefied natural gas inlet / outlet terminal according to claim 1, characterized in that, The top plate of the import / export terminal supports at least the LNG receiving station's berthing equipment, loading and unloading equipment, and personnel activity buildings.

3. The installation method of a gravity-based foundation structure liquefied natural gas inlet / outlet terminal according to claim 1, characterized in that, The top plate of the import / export terminal is provided with an opening to allow the upper equipment to connect to the LNG storage tank and equipment compartment.

4. The installation method of a gravity-based foundation structure liquefied natural gas inlet / outlet terminal according to claim 1, characterized in that, Several layers of insulating material that isolates water vapor are installed between the LNG storage tank and the concrete.

5. The installation method of a gravity-based foundation structure liquefied natural gas inlet / outlet terminal according to claim 4, characterized in that, Heating cables and a temperature control system are pre-embedded in the concrete, and the temperature of the concrete is controlled within a preset range by the temperature control system.

6. The installation method of a gravity-based foundation structure liquefied natural gas inlet / outlet terminal according to claim 1, characterized in that, Before the base plate is constructed, airbags and their inflation pipes are pre-embedded at the bottom of the base plate. The airbags have reserved interfaces at the top to connect with the inflation pipes inside the base plate. The airbags are used to inflate during shipment, fill the space between the base plate and the steel skirt, and then lift the GBS.

7. The installation method of a gravity-based foundation structure liquefied natural gas inlet / outlet terminal according to claim 1, characterized in that, It also includes the following steps: Step 8: Open the dock gate and inject seawater into the prefabricated dock until the water level inside the dock is the same as the sea level; Step 9: Empty the ballast water and activate the airbag system at the bottom of the structure to slowly lift the structure. Step 10: Start the winch to tow the structure from the dock to the sea surface and connect it to the tugboat; Step 11: Re-inject ballast water into the structure for counterweighting to maintain balance during offshore towing transport; Step 12: After the GBS is towed to the installation site, it is positioned using GPS to maintain the designed installation accuracy and tilt limit. After ballast water is injected and the structure sinks to the seabed, other ballast materials are quickly injected to enable the structure to resist wind and waves. At the same time, the air in the airbag is evacuated to create negative pressure under the bottom plate, which accelerates the foundation consolidation speed and completes the installation.

8. The installation method of a gravity-based foundation structure liquefied natural gas inlet / outlet terminal according to claim 1, characterized in that, The input of ballast water is regulated based on the seawater density data in the target sea area, specifically including: The buoyancy information of the gravity-based liquefied natural gas inlet and outlet terminal in the target sea area is calculated based on the seawater density data, and the ballast water volume injected into the gravity-based liquefied natural gas inlet and outlet terminal is obtained. The mass information of the ballast water is calculated based on the amount of ballast water injected into the current gravity-based liquefied natural gas inlet and outlet terminal, and the mass information of the current gravity-based liquefied natural gas inlet and outlet terminal when no ballast water is injected is obtained. The total mass information is calculated based on the mass information of the ballast water and the mass information of the current gravity-based liquefied natural gas inlet and outlet terminals when no ballast water is injected. The deviation rate between the total mass information and the buoyancy information is then calculated. When the deviation rate is greater than the preset deviation rate threshold, the ballast water volume injected into the liquefied natural gas inlet and outlet terminals of the gravity-type foundation structure is adjusted until the deviation rate is not greater than the preset deviation rate threshold.

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